Process for the production of colored polyurethane plastics



United States Patent 3,137,671 PROCESS FOR THE PRODUCTION OF COLOREDPOLYURETHANE PLASTICS Hans Heinrich Bosshard, Binningen, Anton Elsener,Birsfelden, Franz Wirsching, Allschwil, and Heinrich Zollinger,Binningen, Switzerland, assignors to Ciba Limited, Basel, Switzerland, aSwiss firm N0 Drawing. Filed Mar. 16, 1959, Ser. No. 799,443 Claimspriority, application Switzerland Mar. 18, 1958 1 Claim. (Cl. 26037) Itis known that the polyaddition of organic compounds containing reactivehydrogen atoms with organic polyisocyanates leads to the formation ofvaluable plastics, which can be used for a very wide variety ofpurposes, for example, for the manufacture of moulded bodies, foils,fibrous materials, foamed materials, or coating compositions. It is alsoknown to use pigments which are insoluble in organic solvents for theproduction of colored polyurethane plastics. However, as disclosed inGerman Patent No. 1,028,771 of October 1, 1955 to FarbenfabrikenBayer-Aktiengesellschaft, Leverkusen-Bayerwerk, Germany, the use of suchpigments is attended by various disadvantages. For example, in order tobring about a uniform fine state of division of the pigment it must bedispersed in, or ground with, the component containing a reactivehydrogen atom, which necessitates the use of costly apparatus.Furthermore, in many cases the properties of fastness of polyurethanescolored with pigments do not fulfil practical requirements. The factthat many of the pigment dyestufis bleed and have a poor fastness tomigration, over-stripe bleeding, and extraction renders them useless forcoloring polyurethanes.

The present invention is based on the observation that uniformly coloredpolyurethane plastics which are fast to bleeding, migration, over-stripbleeding, and extraction, are obtained by incorporating, before orduring the polyaddition, an organic dyestuff which contains at least onedi-hydroxyethylamino group capable of reacting with the isocyanate underthe conditions of the polyaddition.

As organic compounds containing reactive hydrogen atoms there areadvantageously used polyesters of high molecular weight which containhydroxyl groups, and especially such polyesters obtained from adicarboxylic acid, for example, adipic acid, maleic acid, or phthalicacid, and a glycol, glycerine, trimethylol-propane,hexanetriol-(l:2:6)-diethylene glycol or thiodiglycol. Instead ofpolyesters there may be used polyethers containing hydroxyl groups.

Instead of compounds containing hydroxyl groups there may be usedcompounds containing amino, mercapto or carboxyl groups, or compoundscontaining two or more of these different kinds of groups, for example,hydroxyl and carboxylic acid groups.

The term polyisocyanates includes compounds which contain at least twoisocyanate groups, and especially aryl diisocyanates, for example,naphthylene-l:S-diisocyanate, diphenyl methane diisocyanate andespecially those of the benzene series, for example,phenylene-l24-diisocyanate or 1-methyl-phenylene-2z4 diisocyanate, ormetaor para-xylene diisocyanate, or triisocyanates, for example,compounds of the formula As suitable dyestuffs there may be mentioned,for example, triphenyl methane, oxazine, thiazine, nitro, methine, orphthalocyanine dyestuffs and especially azodyestuifs or anthraquinonedyestufis, and which dyestutfs contain a di-hydroxyethylamino group.Said group may be bound to an aromatic nucleus of the dyestutf moleculedirectly or through a bridge member, for example, an alkylene group, analkylene-amino group, an imino group or a -CO or SO group, for example,as in the group.

Among the azo-dyestufis there may be mentioned, for example,disazo-dyestuffs, and especially monoazo-dyestuffs, for example, those.of the benzene-azo-benzene, benzene azo pyrazolone,benzene-azdacetoacetic acid arylide or benzene-azo-naphthalene series.In addition to the above defined di-hydroxyethylamino groups, theaforesaid monoazo-dyestuiis may contain further substituents of the kindcustomary in azo-dyestuffs and which do not react with isocyanates orreact therewith considerably more slowly than the aforesaid groups, forexample, halogen atoms or alkyl trifluoromethyl, phenolic hydroxylgroups, or alkoxy, acylamino, arylamino, dialkylamino, alkyl-sulfone,carboxylic acid ester, carboxylic acid, sulfonic acid, or cyano groups.

As examples of suitable azo-dyestutfs there may be mentioned dyestuffsof the formulae I OC CH CH OH CON CHZCHQOH Complex metal compounds ofazo-dyestufls can also be used in the process of this invention, forexample, the complex chromium or cobalt compounds of themonoazo-dyestulfs of the formula CHZCHZOH SOzN CHgCHgOH ,For use in theprocess the dyestuif is advantageously dissolved in an inert organicsolvent with good solvent power for the dyestulf, for example, acetone,methyl ketone, ethylacetate, benzene, toluene, nitrobenzene orespecially dimethyl-formamide. The dyestuif solution may be incorporatedeither with the polyhydroxy-compound or with the polyisocyanatecomponent or with the mixture of these two components. In general it isdesirable not to use more than 0.05 mol of dyestuff per mol of thepolyisocyanate compound. In most cases very strong colorations areproduced with a small proportion of the dyestuff, for example, 0.01 m0lof dyestuff per mol of polyisocyanate compound.

When the colored polyurethane plastics obtained by the process of thisinvention for example after dry grinding are to be used as pigments, itis of advantage to use a very large proportion of dyestuif, that is tosay, at least 0.1 mol of dyestuif per mol of polyisocyanate. In certaincases it is of advantage to mix the dyestuff solution with a solution ofthe polyisocyanate component, allow i the mixture to stand for a fewhours, and then to incorporate the polyhydroxy-compound with themixture.

The dyestufls may be used in conjunction with pigments, especially whitepigments, for example, titanium dioxide or a fluorescent body. Insteadof using a single dyestuft of the kind used in the process of theinvention, a mixture of such dyestuffs may be used.

The polyaddition is carried out by the usual methods and may beaccelerated by the use of a catalyst, especially a tertiary amine, forexample, N-rnethyl-morpholine, triethylamine or pyridine.

Colored polyurethanes produced by the process of this invention areuseful for a very Wide variety of purposes, for example, as coatingmaterials, foamed materials or textile coating compositions. As thedyestufl is chemically combined in the polyurethane the colorations arefast to migration and solvents. The dyestutf cannot be extracted even byheating the colored material in a solvent for several hours.

As compared with colorations produced with pigment coloring matterswhich are insoluble in organic solvents, the colorations produced by theprocess of this invention have a higher brilliance. Furthermore, thereis no fear of the dyestufi bleeding out. The colored polyurethanes ofthis invention can also be used as pigments, after converting thecolored polyurethane into a finely divided form.

The following examples illustrate the invention, the parts andpercentages being by weight:

Example 1 20 parts of a medium viscous polyester from adipic acid andtriethylene glycol, known by the trade name Desmophen 2200 [see Bayer:Kunststoife, 1955, page 36] and 6.5 parts of a mixture oftoluene-2:4-diisocyanate and toluene-2:6-diisocyanate are mixed with 1part of a 10% solution of 4-amino-azobenzene in toluene.

The following are then stirred in: 1.9 parts of a mixture of 1 part ofdistilled water, 1.5 parts of a polyglycol ether, and 3 parts of a basiccatalyst, for example ethylmorpholine.

Reaction sets in spontaneously and yields a yellow foamed polyurethaneproduct.

It was found impossible to remove the dyestuff from the foamed productby extraction with solvents.

For the purpose of comparison foamed products dyed withpara-acetaminobenzene were prepared under identical conditions. It waspossible to wash this dyestuff out of the foamed product by extraction.

Example 2 133 parts of a medium viscous polyester from 13 mols of adipicacid, 2 mols of glycerine and 3 mols of butylene glycol, known by thetrade name Desmophen 1100 [see Bayer: Angewandte Chemie, 59, page 264(1947)] and parts of a mixture of toluene-2:4-diisocyanate andtoluene-2:6-diisocyanate are mixed with 50 parts of a solution of 10%strength of 2:4-diamino-4'-dimethylamino-azobenzene indimethyl-formamide. The colored coating material prepared in this manneris used to coat paper with a wet coating 0.2 mm. thick by means of afilm casting apparatus. The lacquer film was allowed to harden at roomtemperature for 2 days.

It was not possible to wash the dyestuff out of the film by extractionwith solvents.

To test the fastness of the colored coating to over-stripe bleeding itwas coated with a nitrocellulose lacquer containing a white pigment.After drying, the top coating was only slightly colored whichdemonstrates the fastness to over-stripe bleeding of the coloredcoating.

In column I of the following table are given a number of furtherdystuifs which, when used in the manner described in this example,produce the tints given in column II which are fast to over-stripebleeding and extraction.

Dyestufi Tint in polyurethane lacquer 1 N=NC -N (GHZC H OH) Yellow.NCON= Omcmomom, Orange.

$11. Cl 3 CHNZSGM WWM CH; 4 OzN-ON=NC N (cmcmoml Red.

| 0 H (|)H CN H 5 O =NC I Greenish yellow.

I SOzN(CH: 20 )2 (I3 1 O H (8-H 6 N=NC I Do.

I 0:N(CH2CH2OH)2 C O O C 2H (6H -Q 7 -N=N0 I C=N Yellow. SO2N(CHzCH20 )23 Chromium complex-from 1 atom of chromium and 2 mols of the monoazo Redorange.

dyestufl of the formula 0 H OH I MG I SO2N(CH:CH2OH)2 I 9 Cobalt complexfrom 1 atom of cobalt and 2 mols of monoazo dyestufi N o. 14 Yelloworange. 10 Chromium complex from 1 atom of chromium and 2 mols of themonoazo Orange.

dyestufi of the formula 0 H OH I I ONE C C ONH SO2N(CH2CH2OH)1 11 Cobaltcomplex from 1 atom of cobalt and 2 mols ofmonoazo dyestufi No.18.Yellow. 12 Chromium complex from 1 atom of chromium and 2 mols of themonoazo Claret.

dyestufi of the formula OH OH SO2N(CHQCH2OH)3 13 Cobalt complex from 1atom of cobalt and 2 mols ofmonoazo dyestuflf No.23. Pink.

E /Q 14 (H O C 11 0 H3) N- N (C H2 C Hz 0 H) 1 Fluoirescent, bnlhant,

Dyestufr Tint in polyurethane lacquer (HO CH1CH2 2N I?T(CH3CH1OH): Blue.

t NH O CH:

16. Copper phthaloeynam'ne tetra [sulfonie acld-dl-hydroxyethylamide]Turquoise blue.

N\ 17 CN=N-C N(CH2CH1O )2 Red.

01110 ONH s tea II I 18 -4 O1N-C N= N(CHzCH:0 Blue.

19 (H0 a a) zNO ozN z Greenish Yellow 20 cH,o- -NHOso,N(oH,oH,oH Yellow.

I NO: NC\ 21 /O=GHQN(CH1OHBOH2)1 D0.

CzHlsO O C CO\ 22 Oi /o=cH- N(orn0rnom, Orange.

NC\ 23 /C=CHQ-N(CHa H2 Greenlsh yellow.

24 O0 0 GH=OH- 3N 01120111011), Yellow with green fluorescence.

25. \Ny -CH=GHON 011,011,011): Brilliant red.

611ml /N 26 CN=N N (01110112011); DO.

Cl S

Dyestuff No. 20 can be prepared as described in US.

Patent No. 2,466,011 of April 5, 1949 to Joseph B. Dickey et :11. byheating 1-chloro-2-nitr0benzene-4-sulfonyl-diethanolamide with 1 mol of1-arnino-4-methoxy-' benzene in the presence of sodium bicarbonate at C.

Dyestuff No. 21 can be prepared by condensing cyanacetic ester withpara-(dihydroxyethylamino)-benzaldehyde in alcohol in the presence ofpiperidine.

Dyestuff No. 22 can be prepared by boiling 1 rnol of 3-hydroxy-thionaphthalene and l rnol ofpara-(dihydroxyethylarnino)-benzaldehyde in alcohol in the presence ofpiperidine.

Dyestuff No. 23 can be prepared by heating 1 mol of Example 3 1 part (1mol) of 2:4-tolylene diisocyanate is mixed with 4 parts ofdimethyl-formamide, 0.01 part of ethylmorpholine is added and the wholeis heated to 100 C. To the hot solution is added dropwise, whilestirring, a solution of 0.2 part (0.1 mol) of the dyestutt of theformula I CHQCHQOH SOzN in 4 parts of dimethyl-formamide. On completionof the addition, the mixture is heated at the boil for 4 hours.

After cooling, 5 parts of a polyglycol ether are added which contains atleast as many hydroxyl groups as are required to saturate the freeisocyanate groups, and the whole is then refluxed for 5 hours. 2 partsof 2:4-tolylene diisocyanate are added, and the mixture is refluxed fora further 6 hours. There is obtained a yellow pigment which is fast tosolvents, and, when brought into a state of fine subdivision bygrinding, colors polyvinyl chloride brilliant greenish yellow tints ofgood fastness to migration.

The dyestufi of the above formula is obtained by coupling diazotized1-amino-3-benzene-sulfonic acid dihydroxyethylamide with3-methyl-pyrazolone-5.

Example 4 Solution I.100 parts of a reaction product from Desmophen 1100(see Example 2) and a mixture of toluene 2:4- and 2:6-diisocyanate,known under the trade name Desmolin [see Bayer: Kunststoffe, 1955, page113] are dissolved in 233 parts of ethyl acetate.

Solution II.12.75 parts of a reaction product of 1 molecular proportionof trimethylol-propane with 3 molecular proportions of a mixture oftoluene-2:4-diisocyamate and toluene-2:6-diisocyanate, for example, theproduct known under the trade name Desmodur L or Desmodur TH aredissolved in 4.25 parts of ethyl acetate,

10 and there is added 0.1 part of Z-methyl-4-diethanolamino-4-nitro-1,l-azobenzene, dissolved in 5 parts of dimethylformamide.

Solution II is allowed to stand for 12 hours at room temperature. At theend of this period the whole of each of solutions I and II are mixedtogether, and the mixture is referred to below as solution III. Ifdesired, special catalysts may be added.

The red solution III so obtained is applied by means of a coatingapparatus in three layers to a cotton fabric, each layer being driedbefore the application of the next layer. The first two layers are driedat 120 C. for 10 minutes, and the third layer is dried at 120 C. for 30minutes.

A fabric, provided in this manner with a colored coating, was allowed toharden completely for 8 days at room temperature, and then tested withregard to resistance to extraction and fastness to migration.

In the test for resistance to extraction the dyestuif could not beextracted from the coated fabric by means of a series of solvents.

The test for fastness to migration was carried out by the sandwichmethod, in which the colored coating was held in contact with foils ofplasticized polyvinyl chloride, regenerated cellulose andacetyl-cellulose at C. under a pressure of 1 kilogram per squarecentimeter for 24 hours. The foils did not become colored, therefore thecolored coating was fast to migration.

What is claimed is:

A process for the production of colored polyurethane plastics obtainedby the polyaddition of an organic compound having two to three alcoholichydroxyl groups with an aromatic polyisocyanate, which comprisesincorporating an organic dyestuff which has a substitutent of theformula OHz-CHr-OH CHz-OHz OH and is dissolved in a solvent which isinert to the dyestuff, thereby bringing about a chemical bond betweenthe dyestufi and the polyurethane.

References Cited in the file of this patent UNITED STATES PATENTS2,225,604 Lubs et a1 Dec. 17, 1940 2,643,958 Kleiner June 30, 19532,894,919 Simon et al. July 14, 1959 2,986,536 Anderson May 30, 1961FOREIGN PATENTS 779,077 Great Britain July 17, 1957 1,158,250 FranceJan. 20, 1958 OTHER REFERENCES Noller: Chemistry of Organic Compounds,page 654, copyright 1951, published by W. B. Saunders Company,Philadelphia, Pa.

